[Resolved] Invisible text boxes

I was wondering if I can make the text fields on my website stand out. At the moment they’re almost invisible and you have to take a good look in order to find them before clicking or tapping to add some text.
I’m not great with php and it would be nice if there was a way to add some code to Additional CSS that would give a darker shade to the text box frames.

Worked like a charm, thank you so much!! And sorry for the late reply.
in case I have more issues, can I post them here or should I open new threads? I just discovered an error on the checkout page (I use Woocommerce) that can’t be replicated with other themes.